The present invention relates to a control method of an internal combustion engine controlled in response to open-close timing and lift amount of air intake and exhaust valves of the engine, specifically to a control method of an internal combustion engine for supporting braking force by means of engine braking.
Conventionally, braking force generated by braking apparatus and supplementary braking force supported by engine brake are used in order to reduce the speed of the motor vehicle. The theory of engine braking is that, as the brake pedal is operated by foot, then the accelerator pedal is released and the throttle valve for controlling the air-intake to the engine is closed, and finally a pumping loss generated due to the negative pressure in the combustion chamber. However, non-throttle engines without throttle valves are used as a system for reducing engine loss in order to increase fuel consumption efficiency.
In non-throttle engines, there occurs such a problem that the braking force generated by engine brake is not strong enough because the gas in the combustion chamber does not have negative pressure and low pumping loss.